Puree prunes adding 1 tbsp of hot water for smoothness. Put in a large mixing bowl. Add the brandy, butter, chocolate, sugar and 250ml boiling water. Put the rest of the water in a saucepan and place the bowl on top until the chocolate melts. Leave to cool for 2-3 minutes.

Sift both flours and cocoa into a large bowl and make a well. Pour in the chocolate mixture then add the whole egg and the egg whites and best to a smooth batter. Bake for 1 hour 15 minutes.